"We recommend you sit towards the back of the ferry – the front moves the most. Ginger can help with seasickness. Ginger ale is available onboard. You may want to talk to a chemist about seasickness tablets.
Bluebridge Ferries have cancelled the majority of their sailings, saying they will likely recommence on Friday morning.
"However, if the large swells continue longer than forecast, further cancellations may occur. We will notify all affected customers as soon as possible if this occurs."
It comes as the capital is battered by a heavy snow watch, with a blasting southerly coming straight from Antarctica.
The polar blast is causing unseasonal, single-digit temperatures across the South Island and into the North Island today - including Auckland, where the temperature in some parts of the city was 9C at 7am.
State Highway 1 Desert Road is closed between Rangipo and Waiouru due to heavy snowfall.
There is a detour in place, via State Highway 49, State Highway 4, State Highway 47 and State Highway 46 for northbound traffic. Southbound traffic should use the same route, in reverse.
Waikato system manager maintenance and operations, Cara Lauder, says despite the recent shift to spring, people should expect winter driving conditions on the road.
